发震断层的永久位移概率评估方法

 基于Cornell地表地震动的概率方法，提出发震断层未来地震引起地表永久位移的概率分析方法，其中断层模型、地震发生模型、震级与破裂面的长度、宽度、地表位移之间关系的参数采用物探结果、震源运动学反演、历史地震资料、现场考察及测年确定。主要技术有2点：(1) 概率分析场点地震动是场点周围断层所有潜在地震的贡献，而场点的地表永久位移仅是该断层的贡献；(2) 场点所在断层发生的所有地震对场点的地震动均有贡献，而场点所在断层发生的少数地震才能对场点永久位移有贡献。应用提出的方法，结合海原断裂地震地质资料和地震活动性资料，给出2种特征地震模型下的不同概率水准的地震地表永久位移。发震断层不同概率水准下的地表永久位移评估为穿越断层的管线和桥梁工程提供基础数据，以便采取合理的抵抗永久地表位移措施，减小地震灾害带来的损失。

A PROBABILISTIC APPROACH TO EVALUATE PERMANENT DISPLACEMENT OF CAUSATIVE FAULTS

A probabilistic approach to evaluate permanent displacement of causative faults is presented based on engineering seismic risk analysis frame work of Cornell，of which the parameters includes the fault model，probabilistic models for earthquake occurrence，the relations among of earthquake magnitude with rupture length，width and surface displacement. The parameters can be determined or verified by results of geophysical prospecting，inversion of kinematics source，historical earthquake data，site investigations and fault dating. In engineering technical points of view，the method adopts two suppositions，one is that all the potential earthquake of fault around the field point contributes to the earquake motion while only the fault contributes to the permanent displacement of the analysis field point；the other is that permanent displacement origins from only a few strong earthquakes on the fault，rather than strong ground motion origins from all earthquakes on the fault. The values of permanent displacement on Haiyuan fault in different probabilistic levels are given by using the data of seismic geology and characteristics of seismic activity. The objective of this research is to determine the value of permanent displacement of causative faults in different probabilistic levels，which have the same probabilistic levels of strong ground motion claimed on the code for a seismic design of buildings and the code for a seismic design of oil and gas steel pipelines of China. Based on the results，the engineers may take measures of to resist the displacement in pipeline and long bridge engineering to minimize loss caused by earthquakes.